Baghdad: Soldiers from an Iraqi army unit in the western province of Anbar have been killed in an apparent `friendly fire` incident, an Iraqi military officer and a police source said on Thursday.

The military source said 22 soldiers had been killed when an aircraft, which he said was from the US-led coalition, bombed the headquarters of an army company on the edge of Ramadi city, Anbar`s provincial capital.

A military spokesman for the coalition said it had carried out an air strike in the area on Wednesday but that it had hit a position held by Islamic State fighters.

"This strike did not result in any friendly casualties," Lieutenant Colonel Thomas Gilleran said.

The Iraq military source said Iraqi aircraft had not operated in the area for two months. "We don`t have any Iraqi war planes carrying out combat duties in Anbar", he said.

An Iraqi police source said dozens of soldiers had been killed in what he described as a friendly fire incident, without identifying the nationality of the aircraft which carried out the air strike.

Iraqi forces have been struggling for more than a year to push back Islamic State militants who control most of the Sunni Muslim Anbar province and swept through northern and central Iraq last June.

The army, backed by militia forces, has launched an offensive to drive Islamic State out of Tikrit, north of Baghdad, but the militants fought back in Anbar on Wednesday, launching at least 13 suicide car bomb attacks on army positions.

The military source said Wednesday`s air strike came after officers appealed for aerial support in response to those attacks.